Casting super strong metals with grain sizes down to nanometers during slow cooling. The study was published in Science Advances For several years, Professor Xiaochun Li has been incorporating dense nanoparticles to make materials stronger and tougher – for example lightweight aluminum alloys and more recently, glass and ceramics. But those enhancing qualities take effect when the material is in its final form. Li started to wonder, “what if nanoparticles could help make super strong metals, during the actual formation?” That is during casting, when they solidify from a hot molten liquid in a mold. That could be a major breakthrough in the casting of metals, a process that is thousands of years old. At the atomic level, atoms of metals group together to form crystal lattices. Those lattices then form units are known as crystalline “grains.” “A grain is kind of like a little family of atoms that are ordered in lattice structure,” Li said. “Metals in their solid form are made up of these many families – each grain has its atomic lattice oriented in one direction, while its neighbors will be ordered in other directions.” “The smaller the grain sizes, the stronger a metal gets,” Li...